title: A modified Bessel filter for amplitude demodulation of respiratory electromyograms.
abstract: We studied a device that is commonly used for amplitude demodulation of respiratory muscle electromyograms (EMG). This device contains a rectifier and a low-pass filter called a modified third-order Paynter filter. We characterized this filter and found that it has good transient characteristics that suit its task as an EMG demodulator, but it has poor high-frequency attenuation that passes interfering, higher frequency components to the output waveform. Therefore, we designed and constructed a new filter with transient characteristics that are comparable to those of the modified Paynter filter but with superior high-frequency attenuation. This new filter is a modified seventh-order Bessel filter. We also identified a simple technique to convert an existing modified Paynter filter back to an original Paynter filter. The original Paynter filter has a wider pass band than the modified Paynter filter but superior stop-band attenuation.
authors.affiliation: Department of Medicine, University of Calgary, Alberta, Canada.
authors.forename: R S
authors.initials: RS
authors.lastname: Platt
authors.forename: E A
authors.initials: EA
authors.lastname: Hajduk
authors.forename: M
authors.initials: M
authors.lastname: Hulliger
authors.forename: P A
authors.initials: PA
authors.lastname: Easton
mesh_terms: D004562:Electrocardiography; D004576:Electromyography / Q000295:instrumentation*; D004581:Electronics / Q000295:instrumentation*; D006801:Humans; D017933:Peripheral Nervous System / Q000502:physiology; D015656:Respiratory Mechanics / Q000502:physiology*